'Baby Fat' May Linger Into Teen Years

May 4, 2006 -- New research shows that "baby fat" isn't just for tots.

Preteens who are carrying extra pounds tend to stay overweight or obese as teens, experts report in BMJ Online First.

Jane Wardle, PhD, and colleagues didn't actually study babies. Instead, they studied more than 5,800 kids from London schools over five years.

The study started in 1999, when the kids were 11-12 years old.

The students' weight, height, and abdominal girth (waist circumference) were measured every year. All measurements weren't available for every child every year, but the data were plentiful enough to show whether kids gained or lost weight as they matured.

The short answer: "Children who are obese when they enter secondary school will very likely leave it obese," write Wardle and colleagues. Wardle is a clinical psychology professor at University College London.

Weight Problems Were Common

Obesity is three times more common in the U.K. and U.S. than it was 20 years ago, Wardle's team notes.

Obese adolescents often become obese adults, the researchers add. Of course, there are exceptions to that pattern. Weight isn't written in stone; a person's future may be different from his past.

At the study's start, nearly a quarter of the students -- who were still preteens -- were overweight or obese. Specifically, between 17% and 19% were overweight; another 6% or 7% were obese.

Girls -- especially black girls -- and kids from low-income families were more likely to be overweight or obese, the study shows.

Extra Pounds Often Stayed Put

Over the years, the researchers found "no change in the rates of overweight and obese combined" and "no reduction in the proportion classed as 'healthy weight.'"

"The number of students who moved from overweight/obese to normal weight (7.6%) was very similar to the number who moved from normal weight to overweight/obese (7.0%)," write Wardle and colleagues.

If extra fat "is present in early adolescence (taken here as age 11), it is highly likely to persist," the researchers write. In other words, preteens' "baby fat" (which the British researchers call "puppy fat") tended to last into the teen years.